Types and origin of dislocations in large GaAs and InP bulk crystals with very low dislocation densities

Abstract

Bulk GaAs and InP crystals with diameter of 4″ or more can now be grown with very low dislocation densities (EPD considerably below 1000 cm–2) using the Vertical Gradient Freeze (VGF) growth technique and rigorous process optimization by the aid of numerical simulation. It turns out that the usually dominating 60°-dislocations are no longer the dominating type if the dislocation density is in the range of EPD = 100 cm–2 or below. The goal of growing large dislocation-free GaAs and InP crystals like Si can only be reached if the types of these “residual dislocations” are identified and their origin is fully understood. This paper therefore reviews the present knowledge about these residual dislocations in GaAs and InP for various dopants. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)